Method for treating bast fibers



A.F.BURKARDT ETAL METHOD FOR TREATING BAST FIBERS Dec. 13, 1955 3 Sheets-Sheet 1 Filed July 6, 1949 AntonF Burkaraf Edward H. Boeg/in y M Ahorneys v Tut Dec. 13, 1955 3 Sheets-Sheet 2 Filed July 6, 1949 A fforn eys Dec. 13, 1955 A. F. BURKARDT EI'AL 2,726,921

METHOD FOR TREATING BAST FIBERS Filed July 6, 1949 5 Sheets-Sheet 3 IIIA )11111, IIIIIIllIIIIl/IIIIIII WWW United States Patent METHOD FOR TREATING BAST FIBERS Anton F. Burkardt, New York, N. Y., and Edward H.

Boeglin, Washington, R. I., assignors to Sativa Corporation, a corporation of New Jersey Application July 6, 1949, Serial No. 103,262

6 Claims. (Cl. 8-156) This invention relates to a method for treating bast fibres of ramie, jute, flax, hemp-or any bast fibres.

While many attempts have been made to improve the art of fiber treatment which resulted in the production of beautiful samples. of yarn and fabrics, only moderate success was achieved in European countries while the efforts in the United States can be termed a complete failure.

The reason for this can be found in the following facts:

(1) The cost of degumming.

(2) The fibre produced under existing methods was uneven. Some strands of fibres were degumrned more or less than others so that different quality of fibers were produced, making the spinning of the fibers into fine counts of yarns impossible.

(3) The methods employed inv degumming these fibers could not be controlled so that fibers of certain staple length could be produced at will.

(4) Special machinery was required to prepare and spin these fibers. This was the main reason why textile mills had rejected these fibers as a basic raw material.

It is known that the packing of fibers caused some of 1 these difiiculties, and the provision of trays into which limited quantities of fiber could be floated to overcome the packing while degumming has been used. Suchmethods, while overcoming some of the above difiiculties, increased the labor cost to such an extent that this method has never become commercially practical.

The object of the method herein disclosed is to overcome all the above-mentioned difficulties and objections.

Other objects will more fully appear from a perusal of the following specification and accompanying drawings in which:

Figure 1 is a diagrammatic view of the layout of the appaartus necessary to practice the invention;

Figure 2 is a sectional view of the web F2 of fiber on the line 2, 2, Figure 1;

Figure. 3 is a sectional view of the web F3 of fiber on the line 3,3, Figure 1;

Figure 4 is a sectional view of the web F4 on the line 4, 4, Figure 1;

Figure 5 is a side view of a pile of webs F5 laid on each other, as placed in the degumming tank 14, Figure l for treatment;

Figure 6 is a transverse sectional view on the line 6, 6, Figure 1, of the degurnming tank Figure 7 is a fragmentary, longitudinal, sectional view on the line 7, 7, Figure 6 of the degumming tank 15; and

Figure 8 is a fragmentary longitudinal view of an alternate form of degumming tank.

Figures 9 and 10 illustrate alternate forms of degumming tanks.

For the sake of illustration the method will be described as applied to hemp fiber suitable for textiles. Preferably this fiber is grown by the method described in the copending application Serial Number 87,594, dated April 15, 1949, but the instant method can be used with other fibers and with fiber grown in any known manner.

It will be understood that where fiber is referred to herein, this term means fiber that has been obtained from the hemp by subjecting the hemp plants or straw to a suitable decorticating or other process whereby the fiber has been separated from the wood substance, the fibrils of the fibers being held together by the natural gum of the plant.

Raw, undegummed fiber F1 is fed in any suitable manner into any suitable device such as the spreader 11 where the fibers are paralleled, lumps and snarls broken up and the fibers formed into a web or bat which is discharged from the spreader via the forming nozzle 12.

At this stage in the process the web bat or roving is approximately of circular cross section and may have a diameter of 4 inches, as shown in Figure 2 and is designated as F2 and is in a comparatively loose fiuify condition.

it will be understood that the designations F1 to F6 inclusive referred to herein, apply to the web or bat throughout and are used to indicate its condition as described at various stages during the processing.

The web F2 is fed to any suitable compressing means such as the rollers 13 whereby it is lightly formed or compressed and may be given a rectangular or any other form. Where the web leaves these rollers it may be approximately 4 inches wide and /4 inch thick and is designated as F3. This forming is merely to facilitate winding.

The web F3 is now fed to a suitable winding machine 14 where several hundred feet of it may be wound in layers, layer over layer to form a web or bat, which may be 4 feet wide and 6 inches thick, now designated F4W.

As the web F4 is discharged from the winder, it may be wound up on itself to form a coil weighing 500 to 1000 lbs. Burlap can be wound up with the coil to prevent the layers from entangling.

Instead of winding the web into a coil, it can be fed into a loop-storage or other device to store it temporarily while tanks 15 and 52 are in operation, as hereinafter described. Such loop storage devices are well known and are not here shown in detail, but one is indicated at 14WS and it will be understood that the web is fed into 14WS, stored herein and fed out therefrom to tank 15.

The web F4 may be fed directly to tank 15, or from the roll into the tank or unrolled on to the floor alongside the treating or degumming tank 15 and cut into lengths that will fit lengthwise into said tank. These lenghs may, for example, be 50 feet long and are piled on top of each other to form a composite bat that will be 50 feet long and 4- feet wide and, if 5 layers are used, 30 inches thick. This composite bat is designated F5 and, like the preceding webs or bats, is relatively long compared to its width.

Referring to Figure 6, the degumming tank 15 is preferably made of stainless steel and has side walls 16, 17 and bottom 18 and end walls. The tank forms a long, rectangular trough. Above the bottom 18 is a perforated false bottom 19 to which is secured stand pipes 20 which may be 3% inches in diameter spaced longitudinally about 22 inches apart and located in the center of the tank.

Extending longitudinally of the tank below the perforated bottom 19 is a steam supply pipe 21 provided with a plurality of vertical nozzles or jets 22, one for each of the stand pipes 20. The pipe 21 has a valve 23 for regulating the admission of steam thereto.

A length of the web F5 is now placed at each side 24, 25, of the longitudinal row of pipes 20 and as these bats are loose and fiufiy, they are expanded so as to fit longitudinally around said pipes to fill all of the space within the tank, the sides of which extend above the bats to form a free space 26 thereabove. While the bat F5 has several layers of bat F4, it will be understood that because the fibers throughout lie loosely and parallel, that the layers merge and the bat F5 becomes one floating mass of fiber.

This floating mass'has just sufficient strength longitudinally to enable it to be withdrawn from the tank endwise as presently described. This eliminates the necessity of handling the bat while it is in the tank and it is never distended while undergoing treatment.

Sufiicient degumming fluid of any suitable character is introduced into the tank 13 via the fluid pipe 27 having a regulating valve 28 therein. The fluid fills the tank and pipes up to the top of the latter, overflows and submerges the bats F5 therein, leaving the free space 26.

As shown in Figure 7 the steam pipes 22 may have horizontal side jets or perforations 29 therein whereby steam is blown into the body of liquid in the space 39 to circulate same longitudinally along the bottom of the tank, but any other fluid circulating means may be employed. Jets 29 causea thorough mixture of the degumming fluid and aid the vertical jets in maintaining said fluid at the proper temperature.

Instead of the constructionshown in Figure 6 and 7, the circulation of the liquid below the bats can be accomplished as shown in Figure 8, where the side or horizontal jets 31 fed from pipe 21 or a separate supply pipe 31 are alternately directed in opposite directions to cause what may be termed a sectionalized circulation of the liquid below the perforated bottom 19. Also, as shown in Figure 9, the upper ends of pipes 20 may be provided with overhead spray nozzles 32. These nozzles are swivelled on the pipe so they can be turned horizontally when filling the tank with fibers. The liquid is fed to these nozzles via the longitudinal pipe 33. The liquid will then be sprayed downwardly on to the bats F5, pass through the perforated bottom 19 and into the space 34 below same, where it is carried ofi via drain pipe 35 to a pump 36 which recirculates same via pipe 37, valves 38, 39 being open the while, and valves 40, Mi closed.

A normally closed charging valve 40 is provided for charging. the tank with liquid. 4th is a normally closed valve for draining the system. In Figure 9 the bats F5 are shown as lying on the bottom 19, being compressed thereon by the sprays from the nozzles 32. This illustrates a washing step which can be employed if desired in the method to be presently described.

The steam coils 41 are located as shown in the lower portion 34 of the tank to heat the fluid if desired. Any of the tanks may be provided with a suitable cover 42, Figure 9, which is lifted oi the tank in a manner that will be obvious and the tanks may be provided with side shelves 43, 44, Figure 9, to facilitate loading. The steam coil 4-1, Figure 9, may also be used with any of the tanks, Figures 7 to inclusive.

Referring to Figure it another type of tank is shown. Here the tank has two lower compartments 45, 46 below the false bottom 19 in communication with each other via holes 47 in partition 48. The holes are of such size compared with pipes 20, that when the liquid in 46 is heated in any suitable manner as by the gas burner 49, the liquid is ejected from the upper ends of pipes and percolates down through the bats F5.

The composite bats F5 made up of layers of F4 being submerged in the degumming liquid in any of the tanks previously described, will be in a loose fluffy condition, as throughout the preceding steps care has been taken to avoid as much as possible compressing or matting the fibers. As a result, the fibers making up the bat are parallel and in a condition to float-more or less individually-in the liquid. As there is no cover or screen over the top of the bats in contact therewith, there is no way for the bats to be compressed thereby and same float in the body of liquid as it circulates through the hat or web.

By regulating the flow of liquid from pipes 20 or nozzles 32, the. vertical circulation or percolation through the bats may be controlled, so that the entire mass of fibers floats free and does not pack on the perforated bottom 19, the fibers separating and tending to float individually in one long floating mass, the fibers being surrounded on all sides by the degumming liquid so that uniform action is obtained, the exposure of the fibers to the liquid being the maximum obtainable.

The bats F5 remain in the boiling degummiug liquid until the desired amount of gum has been removed from the fiber. The length of time the bats remain in the liquid is dependent on the nature of the raw fiber, particularly in respect to the gum content, and the nature of the degumming liquid used. By way of illustration, it will be pointed out that the bats F5 may remain in the tank for an hour and forty-five minutes when known castile soap degumming liquids are used at a temperature of approximately 220 F. Obviously no exact figures can be given for the pressure for nozzles 22, 29 and 32, as that depends upon the degumming fluid used, room temperature, the character of the fiber and other variable factors, but this and the regulation of the whole degumming action which occurs in the tank is easily ascertained by a brief experience with any given installation. Once determined, the process can be repeated with uniform results.

The bats F5 having been treated as just described, they may be withdrawn from tank 15 and passed through the wringer rolls 50 to remove surplus degumming fluid. They may then be fed via rollers 51 to a treating tank 52 in which they may be subjected to a second degumming bath (tank 52 being any of the previously described tanks) or to a plain rinse or boilofi, or any other desired treatment. The bat F5 when it leaves rollers 50 hangs together as though it were a woven fiber and is easy to handle and is now referred to as F6.

The bat F6 may be withdrawn from tank 52 by rollers 53 and delivered to any suitable type of washer such as the roll or squeeze washer 54 where the bat is given a final rinse in a suitable neutralizing solution or water. The rolls 55 of the washer 54 are reversed at suitable intervals to squeeze the web from end to end as many times as is necessary.

The web F6 is removed from washer 54 and placed in a suitable centrifugal extractor 56 to remove the liquid therefrom. The web, as it leaves the extractor, may be designated as F7. The web F7 is now fed through any suitable dryer 57, and the finished web of degummed fiber leaving the dryer is now designated as F8. The web F8 can be opened up and prepared for spinning by a picker, card or other suitable machinery.

Reference has been made to washing the web or bat F5 while in the tank 15, reference being made to Figure 9. To accomplish this is it necessary to close valves 38 and 40, and open valve 40 to drain the degumming fluid. This permits the webs F5 to settle on the screen or perforated bottom 19, where they drain free from degumming fluid. Water is now admitted via valve 40 (or in any suitable manner) and, valves 38 and 39 being open, and valves 40 and 40 being closed, the water floats the webs as did the degumming fluid and same now float as previously described and are sprayed meanwhile by water from nozzles 32, said water being circulated by pump 36 as previously described for the degumming fluid.

The water is gradually withdrawn from the system, the webs again sink and rest on the bottom 19 and the last of the water from sprays 32 percolated through the webs and flows away via valve 40*.

The web may, by this means, be washed in the degumming tank and compacted by permitting it to settle on the screen 19. The compacted web may then be conveyed to tank 52 or direct to the Washer 54, or direct to the extractor or centrifuge 56 or to dryer 57.

The web or bats F5 may be pre-shrunk by the action of the degumming fluid or by the application of water or other fluid thereto while in either tank 15 or 52.

During the one and three-quarter hour treatment referred to, a web F5, 50 feet long, will shrink approximately 8 feet. That is to say, if the web F5 is approximatel 50 feet long when dry, the web F6 leaving the tank after treatment will be approximately 42 feet long. Therefore the web may be degummed and the fiber preshrunk in the same operation. The weight of a web F5 may be 500 pounds and after degumming, the weight of the web (now F6) will be approximately 350 pounds.

It will be seen from the foregoing that the method herein described is a continuous process and one capable of handling a large quantity of fiber. The spreader 11 may discharge directly via nozzle 12 to the winder 14 to produce the roll of web F4W.

Instead of producing roll F4W and then unrolling it and building up bat F5 as previously described, the winding machine 14 may produce the multi-layer web F5, or the web F4 may be fed to any suitable web forming and loop storage device 14WS, where the composite bat or web F5 is produced at a rate necessary to supply tank 15 as needed. From either of the tanks the web F5 may be automatically fed to. a suitable washer 54, extractor 56 and dryer 57.

As suitable conveying mechanisms to carry the web through the various above-described steps are well known, they are not herein described in detail as such details form no part of the method claimed herein.

It will also be observed that the inventive concept of forming the fibers into a long web or bat is most important as it enables hundreds of pounds of fiber to be simultaneously processed without hand labor.

Heretofore the practice has been to employ trays having perforated bottoms and stacked one on the other so as to form receptacles 6 to 7 inches deep, each tray acting as a perforated cover for the one below.

A few pounds of fiber is placed in each tray by hand, the indivadual fibers lying haphazardly and being uncombed and often snarled. The stack of trays is then immersed in degumming fluid which is circulated through the trays from top to bottom, the liquid being prevented from flowing laterally.

Obviously the mass of fiber in each tray is not free to float as it is held either against the top or bottom of the tray, depending on the direction of flow of the fluid. To float fiber so located requires constant watching and hand regulation of the fluid, which is commercially impossible.

The herein described method distinguishes from and is an improvement over the prior art method just described in that there are no trays employed which need frequent cleaning and repair. Instead of hand loading and unloading small batches, each run by the instant method may handle 500 pounds or more in a single loading and unloading operation.

With the instant method the tanks are loaded with fibers which are laid out or combed longitudinally in the direction of the length of the web and which readily separate laterally like strands of hair to permit the circulation of the degumming fluid. No constant hand regulation of the liquid is necessary when treating such fibers, as the fibers float freely and are unrestrained.

There is a current flowing in the tanks, as shown by arrows, Figure 6, which very slowly rotates the bat, thus repeatedly bringing the fibers from the bottom to the top of the tank, thus ensuring thorough treatment of the fiber.

The fibers in the present method not only float freely but the entire mass or web floats and is removed from the tank by a single operation, requiring a minimum of labor.

The second feature of importance herein disclosed is the degumming tank 15 and its modifications. Degumming tanks of the prior art required batch loading of the fiber in comparatively small lots (such as the tray method referred to above) and careful and continuous manual regulation of the flow of degumming fluid was necessary.

Often some mechanical means of agitating the fiber to bring the degumming fluid into proper contact therewith was employed which snarled and often broke the fibers.

None of the prior art devices enabled fibers of the class herein described to be economically and efiiciently degummed, as such devices required excessive hand labor for their operation, frequent loading and unloading and, mainly because the fibers were matted and uncombed when introduced into such tanks, produced non-uniform and unsatisfactory results.

While the long heavy web herein described may be used to advantage with many degumming devices, and while the tanks herein described may be used to advantage with smaller bats or even by filling them with loose fiber, the preferred method is a combination of the long heavy bat and applicants tank.

Other steps herein set forth may be carried out when desired by well known apparatus commonly employed for handling fibrous materials. However, applicants employment of these devices in the sequence claimed is new and useful and results in the production of treated fiber in large quantities at low cost by a continuous process.

In the specification and claims the term relatively long as applied to the webs or bats F1 to F8 inclusive and their tanks, is hereby defined as meaning a bat or tank in which the length is at least 4 times the width. As an illustration, if the bat is 4 inches Wide it will be at least 16 inches long, and if 4 feet wide, at least 16 feet long.

Fiber can be produced of any desired staple length by controlling the flow of degumming fluid through the fiber and regulating the time the fiber is subjected to the action of said fluid. This controls the amount of gum left in the fiber.

Fiber varies in specific gravity. By controlling the flow of the degumming fluid, fiber of any given weight may be kept submerged in a floating position while the fluid circulates in a path perpendicular to the length of the fibers. The rate of flow of the liquid may be made to compensate for the difference in weight of the fiber.

What is claimed is:

l. A method of treating bast fibers, including forming raw undegummed fiber strands into a relatively long dry web of fibers in a comparatively loose flufly condition, said fibers lying parallel to the length of the web; positioning said web horizontally to be treated; floating said web in a bath of degumming fluid; circulating the fluid so as to pass through the web at substantially right angles thereto; removing said fluid from about said web while the latter is stationary; applying wash water to said web to remove degumming fluid and gum therefrom; and drying said Web.

2. A method of treating bast fibers, including forming raw undegummed fiber strands into a relatively long dry web; subjecting said web to a bath of degumming fluid while floating and moving said web horizontally by moving the fluid along paths intersecting the path of movement of the web; removing said fluid from about said web while the latter is held stationary; applying wash water to said web while in said stationary position to remove degumming fluid and gum therefrom; and drying said web.

3. A method of treating bast fibers, including winding a parallel fibrous roving composed of strands of fibers into a heavy dry web; immersing said web horizontally into a degumming fluid and moving said Web longitudinally therein; floating said web while circulating degumming fluid vertically therethrough; and controlling the flow of the circulating fluid to prevent the Web from sinking into said fluid.

4. A method of preparing and degumming bast fibers, including the construction of a paralleled roving of heavy dry individual strands of fibers; degumming said fiber in web form in a bath in which said web is floating and moving longitudinally by moving the fluid along paths intersecting the path of movement of the web; withdrawing said degummed fiber from said bath; washing said fiber in wash water to remove degumming fluid and gum therefrom; drying said fiber; and opening said fiber to produce spinnable fibrils therefrom.

5. A method for treating bast fibers, including forming fibers composed of strands. to be degummed into a relatively long dry web; immersing said web while moving longitudinally in a body of degumming fluid and circulating said fluid through said web, said web being normally floatable in said fluid; and circulating said fluid in a path perpendicular to said web while said web is submerged and floating in said body.

6. A method of treating bast fibers, including flooding a relatively long dry web of fibers composed of strands with degumming fluid while said web is floating stationary in said fluid; causing said fluid to percolate through said web in planes perpendicular thereto while said web is stationary; circulating said fluid below said floating web; withdrawing said web from said fluid; and drying said web.

References Cited in the file of this patent UNITED STATES PATENTS 1,532 Olcott Mar. 31, 1840 867,026 Ellis Sept. 24, 1907 975,116 Bonnin Nov. 8, 1910 988,151 Summers Mar. 28, 1911 1,432,318 Brandwood et al Oct. 17, 1922 1,489,546 Pritchard Apr. 8, 1924 1,584,491 Taylor May 11, 1926 1,737,149 Cohoe Nov. 26, 1929 1,815,279 Takamine July 21, 1931 1,824,928 Pritchard Sept. 29, 1931 2,066,168 Witte Dec. 29, 1936 2,067,497 McCardle et a1 Ian. 12,- 1937 2,084,796 Dwight June 22, 1937 2,130,681 Forsyth Sept. 20, 1938 2,151,363 Wedler Mar. 21, 1939 2,418,995 Thomas Apr. 15, 1947 2,441,390 Boeddinghaus May 11, 1948 2,442,012 Leonard May 25, 1948 2,445,504 Williams July 20, 1948 2,552,078 Williams May 8, 1951 OTHER REFERENCES Review of Textile Progress, vol. H, Great Britain, 1950, p. 24. 

1. A METHOD OF TREATING BAST FIBERS, INCLUDING FORMING RAW UNDEGUMMED FIBER STRANDS INTO A RELATIVELY LONG DRY WEB OF FIBERS IN A COMPARATIVELY LOOSE FLUFFY CONDITION , SAID FIBERS LYING PARALLEL TO THE LENGTH OF THE WEB; POSITIONING SAID WEB HORIZONTALLY TO BE TREATED; FLOATING SAID WEB IN A BATH OF DEGUMMING FLUID, CIRCULATING THE FLUID SO AS TO PASS THROUGH THE WEB AT SUBSTANTIALLY RIGHT ANGLES THERETO; REMOVING SAID FLUID FROM ABOUT SAID WEB WHILE THE LATTER IS STATIONARY; APPLYING WASH WATER TO SAID WEB TO REMOVE DEGUMMING FLUID AND GUM THEREFROM; AND DRYING SAID WEB. 